Claims
- 1. A method for exposing a layout comprising multiple layers on a wafer, characterized by the following steps:
exposing at least one layer photolithographically; aligning the wafer with respect to an electron beam exposure system on the basis of structural features from the photolithographically exposed layer; and exposing at least one further layer with the electron beam of the electron beam exposure system.
- 2. The method as defined in claim 1, in which the wafer is first positioned coarsely with respect to the electron beam exposure system in such a way that a surface area of the previously photolithographically exposed layer that contains selected structural features is located in the deflection region of the electron beam;
the surface area is then scanned in the X and Y direction in spot fashion with the electron beam; the radiation backscattered from the individual spots is detected, and from the intensities of the radiation backscattered from the individual spots an actual data set is obtained that corresponds to a raster image of that surface area with the wafer in the actual position; the actual data set is compared to a stored reference data set that corresponds to the raster image (template) of the same surface area with the wafer in the reference position; from the deviation between the two data sets, information is derived as to the deviation between the actual position and the reference position; on the basis of that information, a positional change of the wafer is caused in order to bring the actual position closer to the reference position; an actual data set is then obtained again and is compared to the reference data set; and the obtaining of an actual data set and the comparison with the reference data set are repeated, as applicable, until no further deviation is ascertained.
- 3. The method as defined in claim 2, in which the reference data set is obtained by means of a wafer that has already been exposed, the wafer and the electron beam exposure system first being displaced relative to one another until the selected structural features are located in the reference position, and a data set corresponding to the raster image of the surface area having those structural features then being acquired and stored.
- 4. The method as defined in claim 2, in which the reference data set is taken from structure data set of the layer that is to be exposed photolithographically, and stored.
- 5. The method as defined in claim 2, in which the surface area having the selected structural features that is scanned in spot fashion in the X and Y directions has a size in the range up to 2000 μm×2000 μm.
- 6. The method as defined in claim 2, in which the actual data set that corresponds to a raster image of the surface area having the selected structural features is obtained from the radiation backscattered from between 20×20 and 1000×1000 spots.
- 7. The method as defined in claim 2, wherein during scanning of the surface area with the electron beam in spot fashion, a step size from spot to spot lies in the range from 20 nm to 5 μm.
- 8. The method as defined in claim 2, wherein during scanning in spot fashion, the surface area is divided into micro-fields that are scanned individually and sequentially and, for purposes of analysis, assembled into an overall image.
- 9. The method as defined in claim 2, in which after agreement has been achieved between the actual data set and the reference data set, a fine alignment of the wafer is performed on the basis of alignment marks present on the wafer.
- 10. A wafer having a layout comprising multiple layers and equipped with structures, comprising:
at least one layer which is exposed photolithographically; and at least one further layer which is subsequently exposed with an electron beam exposure system, wherein the wafer can be aligned on any desired structure on the wafer in the electron beam exposure system, but the wafer does not require any separate structures that serve only for alignment in the electron beam exposure system.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This invention claims priority of the U.S. provisional patent application No. 60/224,979 which is incorporated by reference herein.
Provisional Applications (1)
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Number |
Date |
Country |
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60224979 |
Aug 2000 |
US |